The present invention relates generally to the electrical, electronic and computer arts, and, more particularly, to memory devices and methods of forming such devices.
The maximal ideal density of a two-dimensional memory array is generally achieved with a 4F2 crosspoint array, where F is the minimum resolvable feature size, with a memory cell residing at each unique intersection of perpendicular wiring lines in the memory array. In order to form a crosspoint memory array for resistive memory (e.g., phase change memory (PCM) or resistive random-access memory (ReRAM or RRAM)), each memory element is typically comprised of a memory cell and an access device.
Although it is advantageous to fabricate the memory array with a minimal number of masking steps and processing steps, an adequate number of processing steps of certain types is conventionally required for forming a reliable memory cell. A single pattering using reactive ion etching (RIE) of the memory element and the access device would minimize the number of masking layers and processing steps, however it is often impossible or impractical to pattern the memory element using RIE without also damaging or in some way modifying the memory element during the RIE process.